You can see a mark on lock´s body which states the lock´s status and first disc is marked with an arrow. Normally there is also a led on mounting plate showing if it´s on or off.
Electronic part comes off easily, only two plastic clips keeping it in place. Behind the lock cylinder there is a ball bearing in the center (don´t see why), a spring and a plastic cap with a shape allowing micro switch to go on and off while rotating.
Here is that plastic cap closer
Micro switch is that rectangular-shaped thing near center
This lock operates only momentary and it´s key retaining, there is one disc behind the cylinder preventing it to turn whole 360 degrees. So you turn the key, it either gives an ON or OFF- signal to alarm system depending how it´s wired. If you wire only two furthest away it stays off until you turn the key.
Ýou could do this system also with a standard cam lock operating a switch but I´m curious to hear and see how other lock manufacturers have done their similar products.